Windows uses the index to perform very fast searches of the most common files on your computer. Here are answers to some common questions about the index. (For information about advanced indexing options, see Change advanced indexing options.)

By default, all of the most common files on your computer are indexed. Indexed locations include all folders included in libraries (anything you see in the Documents library, for example), e‑mail, and offline files. Files that aren't indexed include program files and system files—files that most people rarely need to search.

The easiest way to add something to the index is to include a folder in a library. When you do that, the content in that folder is automatically indexed. For more information, see Include folders in a library.

You can also add something to the index without using libraries. To add or remove an index location:

Open Indexing Options by clicking the Start button , and then clicking Control Panel. In the search box, type indexing options, and then click Indexing Options.

Click Modify.

To add or remove a location, select or clear its check box in the Change selected locations list, and then click OK.

If you don't see all locations on your computer in the list, click Show all locations. (If all locations are listed, Show all locations won't be available.) If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

If you want to include a folder but not all of its subfolders, click the folder, and then clear the check box next to any subfolder that you don't want to index. These folders will appear in the Exclude column of the Summary of selected locations list.

The Windows search index improves the efficiency of searches by keeping track of file names and other information for most of the files stored on your computer. It's best to let the index run uninterrupted in the background, but you can pause it for 15 minutes at a time.

To pause the index

Open Indexing Options by clicking the Start button , and then clicking Control Panel. In the search box, type indexing options, and then click Indexing Options.

Click Pause. If you're prompted for an administrator password or confirmation, type the password or provide confirmation. (The index must be running in order for the Pause button to be available.)

You shouldn't do this. If you make the index too large, or if you include system file locations (such as the Program Files folder), your routine searches will slow down. For best results, we recommend that you only add folders that you search frequently.

It might be because of the security settings for that folder. For a folder and its content to be indexed, it must be configured with the System permission. Most folders already have this, but there are some cases where a folder might be missing the System permission.

To add the System permission to a folder

Right-click the folder, click Properties, and then click the Security tab.

If you don't see System listed under Group or user names, click Edit.

Click Add, type System in the box that appears, and then click Check Names.

Under Matching names, click System, and then click OK until all of the open dialog boxes you've opened are closed.

If you are experiencing problems with searching, such as unusually slow searches or incomplete search results, run the Search and Indexing troubleshooter to see if it can diagnose the problem.

Open the Search and Indexing troubleshooter by clicking the Start button , and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Click View all, and then click Search and Indexing.

Depending on the severity of the problem, the Search and Indexing troubleshooter might need to restart the Windows Search service.

You might need to install the File Services role on your computer before all search and indexing options are available. You can do this from the Server Manager console. To open the console, click Start, type Server Manager into the search box, and then click Server Manager. For more information about installing the File Services role, in the Server Manager console toolbar, click Roles, and then click Roles Summary Help.

Similar to the way the index in a book helps you to keep track of its contents, the index in Windows keeps track of the files on your computer. The index stores information about files, including the file name, date modified, and properties like author, tags, and rating. You will never see the index, but it is used by Windows to perform very fast searches of the most common files on your computer.

The index is used to make searching for files much faster. Instead of looking through your entire hard disk for a file name or file property, Windows scans the index, which allows most results to appear in a small fraction of the time that a search without the index would take.

By default, all of the most common files on your computer are indexed. Indexed locations include all of the files in your personal folder (such as Documents, Pictures, Music, and Videos), as well as e‑mail and offline files. Files that are not indexed include program files and system files. The locations that contain those files are not indexed because you rarely need to search those files, and so not including them in the index makes your searches perform faster.

Open Indexing and Search Options by clicking the Start button , clicking Control Panel, clicking System and Maintenance, and then clicking Indexing Options.

Click Modify.

To add a location, select its check box in the Change selected locations list, and then click OK.

If you don't see all of the locations on your computer in the Change selected locations list, click Show all locations. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.

If you want to include a folder but not all of its subfolders, expand the folder, and then clear the check box next to any folder you don't want to index. These folders will appear in the Exclude column of the Summary of selected locations list.

You shouldn't. If you make the index too large, or if you include system file locations like the folder called Program Files, your routine searches will slow down because the index will not perform well. For best results, we recommend that you only add folders to the index that contain your personal files.

Your index requires virtually no maintenance. However, if the index has problems finding files that you know should be located in an indexed location, you might need to rebuild the index. This can take a long time to complete, so avoid performing this step unless you have given the index enough time (several hours) to correct any problems first. To rebuild the index:

Open Indexing and Search Options by clicking the Start button , clicking Control Panel, clicking System and Maintenance, and then clicking Indexing Options.

Click Advanced, click the Index Settings tab, and then click Rebuild. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.

If you choose to add encrypted files to the index and you are not using a full volume encryption solution for the location of the index, encrypted data from your files—for example, text from a Microsoft Word document—will be added to the index. The index is obscured so that it is not easily readable if someone tries to open the index files, but it does not have strong data encryption. If someone were to gain access to your computer, they could extract your data from the index. Therefore, the location of the index should also be encrypted to help protect your indexed data.